A sensor arrangement of the type in question and a rolling bearing arrangement of the type in question are known from WO 2011/134955 A2 nationalized as U.S. Pat. No. 9,329,022. The rolling bearing arrangement of the type in question is shown in a perspective cross-sectional representation in the attached FIG. 2. The rolling bearing arrangement primarily comprises a rolling bearing 01, axially adjacently to which an angle sensor 02 is attached. The rolling bearing 01 comprises an inner ring 03 and an outer ring 06 which is rotatable about the inner ring 03 about a rotational axis 04. Rolling elements 07 in the form of balls are located between the inner ring 03 and the outer ring 06. The rolling elements 07 are held in a cage 08 (shown in FIG. 3). The space between the outer ring 06 and the inner ring 03 is sealed toward the outside by a sealing disk 09.
The angle sensor 02 includes a sensor ring 11 which is fastened on the outer ring 06, with the aid of a holding element 12, in a peripheral groove 13 formed in the outer ring 06. In this case, the sensor ring 11 is not fastened on the outer ring 06 in a rotationally fixed manner, however, since the annular holding element 12 can rotate in the peripheral groove 13 about the rotational axis 04. The fastening is designed not to be rotationally fixed because the outer ring 06 is rotated slightly in the machine element (not shown) accommodating the outer ring 06 during a relatively long operation. The sensor ring 11 can retain its angular position on the rotational axis 04 due to the fact that the fastening is designed not to be rotationally fixed, and so the measurements carried out using the angle sensor 02 are not corrupted.
The angle sensor 02 also includes a material measure, or material element, 14 which is fastened to the inner ring 03 in a rotationally fixed manner in a peripheral groove 16 formed in the inner ring 03. The material measure 14 has an eccentric annular shape and is shown in detail in FIGS. 6 to 9. The material measure 14 closes the U-shaped cross-sectional shape of a U-shaped pot core 17 which is fastened in the sensor ring 11. The annular pot core 17 consists of a ferromagnetic material. The U-shaped cross-section of the pot core 17 forms a radially inner U-limb 18 and a radially outer U-limb 19 which are angled with respect to a U-base 21.
The sensor ring 11 includes an inner support ring 22 and an outer support ring 23, wherein an annular space 24, in which the pot core 17 and a circuit board 26 are located, is formed between the inner support ring 22 and the outer support ring 23. The circuit board 26 is shown in detail in FIG. 4. A transmitting coil 27 (shown in FIG. 4) and receiver coils 28 (shown in FIG. 4) are formed on the circuit board 26. The transmitting coil 27 and the receiver coil 28 can be electrically connected via a cable 29. The cable 29 is routed out of the annular space 24 via a cable holder 31 on the pot core 17 through a recess 32 in the outer support ring 23. The cable holder 31 is also used for fixing the pot core 17 and the circuit board 26 in a rotationally fixed manner with respect to the machine element (not shown) accommodating the rolling bearing arrangement.
FIG. 3 shows a cross-sectional representation of the rolling bearing arrangement shown in FIG. 2.
FIG. 4 shows, in detail, the circuit board 26 shown in FIG. 2. The transmitting coil 27 and the receiver coils 28 are formed on the circuit board 26. The circuit board 26 is a printed circuit board which has several layers, wherein the transmitting coil 27 and the receiver coil 28 are designed as strip conductors 36. The circuit board 26 comprises four evenly distributed and similarly designed openings 37. The openings 37 each have the shape of a circular ring segment. The circular ring segments each have a central angle of approximately 60°. The outer U-limb 19 of the pot core 17 is routed through the openings 37, and so the pot core 17 completely surrounds the transmitting coil 27, while said pot core surrounds each of the receiver coils 28 approximately only half-way. The outer U-limb 19, which is annular per se, has an interrupted annular shape, and so it can extend through the openings 37. Ring segments 38, each of which has the approximate shape of a circular arc, are formed due to the interruptions in the annular shape of the outer U-limb 19. The circular arcs each have a central angle of approximately 60°.
FIG. 6 shows an embodiment of the material measure 14 of the type which is known for the rolling bearing arrangement from the prior art, which is shown in FIG. 2. The material measure 14 is represented in a cross-section perpendicular to the rotational axis 04, wherein the radially outer U-limb 19 and the radially inner U-limb 18 are also represented. During a twisting of the material measure 14 with respect to the pot core 17 (shown in FIG. 2), said material measure results in a variable reluctance of the magnetic circuit formed by the pot core 17 and the material measure 14 with respect to some of the receiver coils 28 (shown in FIG. 4), since the material measure 14 is eccentric. The eccentricity of the material measure 14 is due to the fact that a ring width of the annular material measure 14 changes around the periphery, namely from a minimum ring width toward a maximum ring width and back to the minimum ring width.
FIG. 7 shows, in detail, the material measure 14 shown in FIG. 2. In contrast to the material measure shown in FIG. 6, the material measure 14 in FIG. 7 has a double eccentric design, since both the outer circumference of the material measure 14 and the inner circumference of the material measure 14 are eccentric. As a result, the angle sensor 02 (shown in FIG. 2) is more insusceptible to displacements of the U-limbs 18, 19 perpendicularly to the rotational axis 04.
The embodiment of the ring segments 38 (shown in FIG. 4) is not shown in the outer U-limbs 19 shown in FIG. 9 and FIG. 10.
The rolling bearing arrangement shown in WO 2011/134955 A2 allows for absolute angular measurements between 0° and 360°. As a result, it is suitable, for example, for supporting a shaft of a unipolar electric motor. The angle sensor 02 shown in FIGS. 2 to 4 is therefore also characterized as unipolar.
A sensor arrangement comprising a multipolar angle sensor is known from DE 10 2012 223 942 A1, which angle sensor is provided for carrying out measurements via n poles, and so angular measurements within rotational angles having the size 360°/n are made possible. The multipolar angle sensor is to be assigned to the same type as the angle sensor shown in WO 2011/134955 A2.
FIG. 8 shows a material measure 14 of the multipolar angle sensor known from DE 10 2012 223 942 A1. This is the material measure 14 of a bipolar angle sensor. The material measure 14 is eccentric, wherein a ring width of the annular material measure 14 along its circumference has two minima and two maxima.
FIG. 9 shows the material measure 14 of a further embodiment of the multipolar angle sensor known from DE 10 2012 223 942 A1. The material measure 14 shown in FIG. 9 differs from the material measure shown in FIG. 8 in that it has a double eccentric design.